SelectCast: Anycast in Path Aware Networks

With the growing availability of path-aware networks (PANs) and the emergence of commercial services built on top of them, there is an increasing need for an anycast primitive that fits this new paradigm. However, implementing anycast in PANs presents a fundamental challenge: PANs rely on source-based path selection, which conflicts with the network-driven path selection used in today’s anycast deployments. This misalignment calls for a rethinking of how anycast should be designed for path-aware architectures. This project develops SelectCast, a mechanism that implements anycast for path-aware networks. SelectCast embraces the end-to-end principle, giving senders greater control to select replicas and paths that align with their application-specific requirements and performance goals. With SelectCast, anycast becomes more than just "routing to the nearest replica" - our approach offers the opportunity of a programmable selection mechanism where clients can express preferences over annotated paths, and application providers can enforce policies about who gets routed where. For instance, a service might expose replicas in Europe and Asia, but restrict access to each based on regional compliance requirements or path trust levels. Meanwhile, clients can steer their traffic to paths with lower delay, higher availability, or within trusted ASes.